FIG. 5 shows an outline configuration of a conventional drinking water server. As shown in the diagram, the drinking water server of this type is composed to store the drinking water supplied form a water bottle (a) filled with drinking water temporarily in a hot water tank (b) provided with a heater (h) and in a cold water tank (c) provided with a cooler (not shown). Pour tubes (d), (e) for taking out the drinking water are connected to the tanks (b), (c), and pour valves (f), (g) are provided at the leading ends of the pour tubes (d), (e).
In the case of such configuration of temporary storage of drinking water in the tanks (b), (c), it is necessary to prevent growth of bacteria in the tanks (b), (c), and in the drinking water server of this type, therefore, as shown in the drawing, it was proposed to stock the drinking water supplied from the water bottle (a) once in the hot water tank (b) by way of a drinking water feed tube (i), and sterilize by heat in the hot water tank (b), and feed into the cold water tank (c) by way of a second drinking water feed tube (j) (see, for example, Japanese Patent Application Laid-Open No. 2006-347556).
However, even in this case of sterilizing the drinking water supplied into the cold water tank (c) by heat, bacteria may grow in the cold water tank (c). Accordingly, in the conventional drinking water server, it was proposed to sterilize in the cold water tank (c) by providing the cold water tank (c) with an ultraviolet lamp (k) for emitting ultraviolet rays (see, for example, Japanese Patent Application Laid-Open No. 2006-62720). It was also proposed to install an ultraviolet lamp closely to the pour valve (g) for pouring cold water (within the pour tube (e)), not inside the cold water tank (c)) (see, for example, Japanese Patent Application Laid-Open No. 2000-128292).
However, the conventional configurations had the following problems, and improvements have been desired.
That is, in the configuration of installing an ultraviolet lamp closely to the pour valve (g) for pouring cold water, bacteria may grow inside the cold water tank (c), and the tank wall may be slimy. Also, in the configuration of installing an ultraviolet lamp in the cold water tank (c), ultraviolet rays are not emitted into the inside of the pour tube (e) of cold water, and bacteria may grow in the pour tube (e).
Moreover, in the conventional drinking water server, the electromagnetic valve used as the pour valve (g) is designed to close a valve body (m) by making use of water pressure in the pour tube (e) as shown in FIG. 6, and if the valve body (m) is kept closed, a large amount of water may circulate and stay in a rear part (n) of the valve body (m). As a result, bacteria may grow in the rear part (n) of the valve body (m).
The present invention is devised in the light of such problems, and it is hence a primary object thereof to present a drinking water server having a structure capable of suppressing generation of bacteria in the cold water tank of the drinking water server, in the cold water pour tube, and in the pour valves.